Insulator



(No Model.)

L. McGARTHY.

INSULATOR.

Patented July 5 s on. mowmma, WASHINGYON. u. c.

UNITED STATES PATENT OFFICE LOUIS MCCARTHY, OF BOSTON, MASSACHUSETTS INSULATOR.

SPECIFICATION forming part of Letters Patent No. 478,518, dated July 5, 1892. Application filed April 19, 1892- Serial No. 429,734. (No model.)

To all whom it may concern:

Be it known that I, LOUIS llIOOARTHY, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Insulators, of which the following is a specification, reference being had therein to the accompanying drawings.

My invention has for its object to provide a durable insulator of high efficiency particularly adapted to outside use where it is required to withstand changes in temperature and the effects of moisture; and it consists in an insulator having the metallic portions insulated by the interposition of sheets of mica laid and pressed together, said metallic portions and interposed mica being suitably secured together and the whole being embedded in an insulating composition contained within a metallic protecting-case, all as hereinafter more particularly set forth, and the novel features of which are pointed out in the claim, which is appended hereto and made a part hereof.

I have shown my invention in the accompanying drawings as embodied in a trolleywire hanger or insulator, such as is employed in the overhead construction of electric railways.

In the drawings, Figures 1 and 2 are vertical sections showing two forms of trolley-wire hanger, some portions thereof being shown in elevation. Fig. 3 is a similar view on a smaller scale, showing a modified form of construction.

My invention will be readily understood from the following description, in which reference is made to the said drawings.

A is a metallic bell or case, which forms an exterior protection for the device and which enables it to withstand a severe blow without injury. The bell or case A is provided with suitable arms b, which are either secured directly to the bell, as shown, Fig. 1, or to a projection from the bell, as shown, Fig. 2.

In Fig. 2 the projection is formed by the end of the bolt (I, which projects through the top of the bell. The metallic portions which are insulated from each other are shown in the form of bolts (1 f, the proximate ends of which are flanged in the usual manner and which are separated by a series of sheets of mica, which are interposed between the proximate faces of the flanged portions. A number of sheets of mica which are cut away centrail y to accommodate the head of the flan ged portion of the bolt (Z are placed around the said flanged portion, and another series of sheets which are cut away to accommodate the body of the bolt are placed or strung on the bolt and cover a portion of said bolt, as shown. A metallic shell or case 9 of a size adapted to receive the sheets of mica is provided and the bolt (Z and sheets of mica are placed therein. The case g is provided at one end with a large opening through which the bolt (Z may pass without coming in contact with said case. The other end of the caseg is screw-threaded to receive a correspondingly-threaded head or flanged portion of the boltf. The head of the boltfis screwed into the case g, and the whole insulation thus formed is secured within the metallic case A by screwing the end of the bolt (1 into the top of the bell or case A or by riveting it therein. A mass of insulating composition 13, which may be of any of the well-known compounds now in use, is then placed in a plastic state inside the case A and is pressed and molded entirely around the insulated bolts (Z f therein, leaving only the downwardly-extending portion of the bolt f exposed. The composition B is then allowed to set and harden. To the lower end of the boltf the trolley wirelc is secured in any wellknown manner. By thus embedding the insulated portions (Zf and their connecting and securing parts, as also the interposed mica insulation, in the insulating composition B the parts are thoroughlyprotected from moisture and the injurious influence of the weather, and a very durable and efficient insulator is obtained.

At Fig. 3 I have shown still another form of trolley-wire hanger, which embraces a bell A and a somewhat different form of interior construction. In constructing an insulator as shown, Fig. 3, the bolt f is provided with an annular shoulder or collar p. A series of sheets of mica g are then strung on the bolt and adjacent them another series of sheets of mica q of less diameter than the series of sheets q. Outside the series of sheets q is placed a ring p of metal, the central aperture thereof being of a size to receive the series of screwed onto the boltf. The bolt f is thus insulated from the ringp; The whole is then placed within the bell A, which may be provided with a shoulder at 19 against which the ring is placed. The securing-flange p is then pressed up against the under side of the ring, thus holding the parts securely within the bell. The ringp is provided with a series of apertures or holes h to permit of the plastic composition flowing or being pressed into the space above the ring within the bell. The plastic composition is then applied, pressed into place, and allowed to harden, firmly embedding the whole of the contents of the bell in a mass of insulating composition.

I do not desire to limit myself to any particular form or construction of the parts or any specific method of securing the metallic port-ions which are insulated by the interposed sheets of mica together, as any Wellknown construction may be employed.

Vhat I claim is An insulator comprising metallic portions separated by an interposed series of sheets of mica compressed together, securing devices by which said metallic portions and said mica are secured together, a mass of insulating material in which said metallic portions and said sheets of mica and their securing devices are embedded, and an outer metallic covering or case, substantially as shown and described.

In testimony whereof I affix my signature in presence of two witnesses.

LOUIS MCCARTHY. Witnesses:

WM. A. MAOLEOD, ROBERT WALLACE. 

